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Original question:

DS90UB949-Q1: Using GPIO as input

DS90UB949-Q1: GPIO output

Bruce Deng
Prodigy 90 points
Part Number: DS90UB949-Q1
Other Parts Discussed in Thread: DS90UB948-Q1, DS90UB947-Q1

I'm trying to use the remote GPIO, but can't seem to find which bit to set an output. I see that the register 0x0D[3:0] should be set to 0x3, but it doesn't indicate where to change the output between high and low. 

  • 0
    TI__Guru** 108530 points

    Hello Bruce,

    please refer to the datasheet "Table 3. GPIO_REG and GPIO Local Enable and Configuration"

  • 0 in reply to Hamzeh Jaradat
    Prodigy 90 points

    Hello, I saw that table, but it is titled local enable and configuration. I would like to use the remote GPIO option and control output at the 948 deserializer from the 949 serializer. My confusion comes from the values in Table 1 and 3, because for example table 3 indicates for GPIO0 to be input 0x0D[3:0] = 0x3. However, table 1 indicates for GPIO0 to be output (forward channel) 0x0D[3:0] = 0x3. Which one should I use for remote GPIO control?

  • 0 in reply to Bruce Deng
    TI__Guru** 108530 points

    Hi Bruce,

    Can you specify which SER and which DES are you using? and where is the GPIO should be as input and where should be the output?

  • 0 in reply to Hamzeh Jaradat
    Prodigy 90 points

    I am using the DS90UB949-Q1 Serializer and DS90UB948-Q1 Deserializer. 

    On the 949 datasheet, section 7.3.15.1 says the IO can be used in a "forward channel (outputs)" mode. In table 1 of the same section, GPIO0's configuration shows that the Serializer should be configured such that 0x0D[3:0] = 0x3 for the forward channel. 

    Later on in the 949 datasheet, section 7.3.15.3, Table 3 indicates that the GPIO0 configuration should be 0x0D[3:0] = 0x3 to make the port have an input function, which contradicts the previous section where 0x3 should be set to use the channel as a forward (output) function.

    Back to my original question, I would like to configure the GPIO for remote output functionality. I would like to command outputs on and off on the 948 deserializer through FPD-LINK from the 947 serializer. Based on the datasheet, I am unclear on how local register 0x0D should be set to achieve this, and I am unclear on what bit to toggle on the 947 side to change the output between high and low on the 948 side. 

  • 0 in reply to Bruce Deng
    TI__Guru** 108530 points

    I am working on this. Will provide feedback shortly

  • 0 in reply to Hamzeh Jaradat
    TI__Guru** 108530 points

    Hello Bruce,

    What is stated in the SER datasheet 7.3.15.1 is not accurate. This is a typo and will be corrected. This sentence should say: forward channel (Inputs) or back channel (Outputs).
    And for you to configure the GPIO0 as an Input on the SER and GPIO0 as an output on the DES you should use the configuration as shown in Table 3 on the SER.

    SER: reg 0x0D[3:0] = 0x03
    DES: reg 0x1D[3:0] = 0x05

  • 0 in reply to Hamzeh Jaradat
    Prodigy 90 points

    Hello,

    Thank you for the clarification. I would like to confirm that the wording in section 7.3.9.1 of the DS90UB948-Q1 datasheet, and the wording in section 7.3.10.1 of the DS90UB947-Q1 datasheet is also inaccurate? 

    Secondly to confirm, I should use Table 3 values to toggle the remote output between high and low? SER: 0x0D[3:0] = 0x1 for low, 0x0D[3:0] = 0x9 for high?

  • +1 in reply to Bruce Deng
    TI__Guru** 108530 points
    Bruce Deng said:
    the wording in section 7.3.10.1 of the DS90UB947-Q1 datasheet is also inaccurate? 

    Yes, same thing.

    Bruce Deng said:
    Secondly to confirm, I should use Table 3 values to toggle the remote output between high and low? SER: 0x0D[3:0] = 0x1 for low, 0x0D[3:0] = 0x9 for high?

    This is correct